Under the legacy MHL 1/2 protocol, a local MHL device communicates with a peer MHL device using a legacy MHL (MHL 1/MHL 2) link. The legacy link, in turn, has a half-duplex legacy control bus that enables exchange of control packets between the local and peer MHL devices. Additionally, in a legacy MHL device, legacy device software interfaces with a half duplex translation layer and therefore also receives or transmits control data in half duplex. Thus, in the legacy MHL 1/2 configuration, the local MHL device, the peer legacy device, the local and peer device software, as well as the legacy MHL control bus are all configured to operate in half-duplex.
Under the MHL 3 protocol, a local MHL 3 device communicates with a peer MHL 3 device using an MHL 3 link that includes a full-duplex enhanced control bus (eCBUS). Additionally, the MHL 3 device has the capability to interface with legacy MHL software through a half-duplex translation layer. But the half duplex nature of the translation layer could result in data transfer conflict, for instance, when packet receive requests arrive at the local MHL 3 device while the local device is already in the process of transmitting control data to a peer device.